Breaking petroleum emulsions



Patent ed Oct. 21, 1941 BREAKING PETROLEUM EMULSIONS Charles F. Bonnet, Monrovia, Calif., assignor to American Cyanamid & Chemical Corporation, New York, N. Yi, a corporation of Delaware No Drawing. Application January 30, 1941, Serial No. 376,628

Claims.

This invention relates to the breaking or resolution of oil field emulsions of the water-in-oil type by the addition of chemical demulsifying agents thereto. A principal object of the invention resides in the treatment of certain emulsions of this class with a chemical demulsifying agent adapted to be effective for the separation of substantial quantities of water therefrom.

The great majority of oil field emulsions-are of the water-in-oil type; that is, they consist of small water droplets surrounded by a continuous oil phase. It is well known that there is a great difference between the stability and difficulty of resolution of emulsions obtained from difierent oil wells, and sometimes even in emi'llsions obtained from the same well at different times. The increased difliculty in resolving some of these emulsions has been ascribed to the presence of cyclic compounds in the oil which tend to surround the water droplets and act as emulsion stabilizers. The present invention is directed specifically to the resolution of petroleum emulsions of the water-in-oil type in which this condition exists.

Studies of oil fieldemulsions of the type found in California lead to the conclusion that the emulsion is stabilized by colloidal micelles which are usually cyclic in character and may be aromatic, cycloparamnic, naphthenic, mixed aromatic-naphthenic, mixed naphthenic-aliphatic, etc. All these compounds contain rather weak hydrophile groups of the type of OH or COOH which cause them to form films surrounding the water droplets at the oil-water interface. They also appear to have relatively strong aflinities for positive ions such as sodium ions and may form soap-like compounds with the inorganic salts dissolved in the emulsified water by reason of their polar groups. It is probable that there is no quantitative formation of soap, but more likely there exists at the oil-water interface a dynamic equilibrium of soap. naphthenic acids, mineral salt anions and cations. and

for many years that all the organic sulfonic acids and their functional derivative which have the properties of commercial wetting agents are eilective to displace at least some of the COONa and RONa groups at the interfacial film and, at the same time, to reduce the surface tension of the water droplets, whereby breaking of the emulsion is facilitated. I

My present invention relates to the breaking of oil field emulsions by subjecting them to the action of an enitrely diiierent class of demulsifying agents; namely, the class of aromatic nitroso compounds selected from the group consisting of nitrosophenols and nitroso aromatic carboxylic acids. I have discovered that the compounds of this class are eflective for inducing the reso-- lution of petroleum emulsions of the type described above; that is to say, emulsions which contain cyclic compounds that appear to act as emulsion stabilizers.

Although my invention is not limited to a specific theory of operation, I believe that the surprisingly good properties of the nitrosophenols and nitroso aromatic carboxylic acids ,as emulsion breakers is due in large measure to the fact that they are acidic organic compounds which appear to have a specific 'actionin disother important factor in their ability to penetrate and disperse the cyclic asphaltines, naphthenic and cycloparafiflnic bodies and other emulsion stabilizers that occur naturally in crude petroleum and thus to bring about the resolution of the emulsion.

Representative nitroso aromatic carboxylic acids which may be used in practicing the invention are the various nitroso benzoic acids, such as ortho-, metaand paranitroso benzoic. acids. and their salts, esters and halogen substitution products. Nitrosophenols which may be used inelude ortho-, metaand paranitrosophenol, the corresponding nitroso cresols and other alkyl phenol and the corresponding alkali metal salts and anisols or other ethers. These compounds may be added as such orin solution in benzol.

cresol. Xylenol or other suitable solvents.

Although the nitroso aromatic compounds of the class described are eflective when used as the sole demulsify s agent, I have found as an aidlitional feature of my invention that these com- )ounds will frequently improve the efliciency of [emulsifying agents of the surface active type, men as sulfonated glyceride oils of the type of rulfonated castor oil, sulfonated corn oil, sulonated olive oil, sulfonated soya bean oil, sulonated linseed oil and the like, as well as sulonated mineral oils such as mahogany sulonates. They may also be employed in admix vure with compounds of the synthetic detergent ind wetting agent type that are known to pos- :ess the property of lowering the surface ten- ;ion of water and aqueous inorganic salt solu- ;ions such as alkyl naphthalene sulfonates, esters If sulfopolycarboxylic acids such as sodium dictyl sulfosuccinate, higher alcohol sulfates, etc. they may also be used in conjunction with or in admixture with other wetting and demulsifying igents such as polyalkyl, aryl or hydroxyaryl iaphthalene, monoor polysulfonic acids and ;heir salts and condensation products, with higher aliphatic or cyclo aliphatic substituted or un- :ubstituted amines, amides or ketones', or with lldehydes such as formaldehyde or with polyiydric alcohols, or with higher unsaturated or iydroxy fatty acids or their salts, esters or miides. Another class of compounds with which hey may be used are the condensation products if alkylene oxides with aliphatic monoand poly- :arboxylic acids, either unsulfonated or sulonated, such as the products obtained by conlensing ethylene oxide with stearic or oleic acids Followed by sulfonation.

It is well known that the acid character of Jhenols and aromatic carboxylic acids is in- :reased by the introduction of nitroso groups, ind the increase in acidic properties is proporional to the number of nitroso groups introluced. For this reason I prefer to employ com- )OllIldS which contain a plurality of nitroso Iroups, such as the trinitrosophenols and triniwosobenzoic acids, but the corresponding com- Jounds containing 1 or 2 nitroso groups may also re employed. Similar results are obtained with ;he corresponding homologs; thus, for example, nixtures of various cresols and phenols such as ire obtainable from coal tar fractions may be .ransformed into the corresponding nitroso com- Jounds by reaction with nitrous acid and these ire attractive compounds for use in practicing ny invention by reason of their relatively low Jrice. Another class of phenols that may be reacted with nitrous acid and used are on and B iaphthol. These compounds may be used as :uch or in the form of their functional deriva- ;ives; thus, in the case of nitroso phenols the :orresponding alkali metal phenolates or ethers nay be employed. The salts and esters of the iitroso substituted aromatic carboxylic acids nay be used in place of the free acids if desired,

and both classes of compounds may be further substituted as by a halogen, in order to further modify their properties.

The aromatic nitroso compounds of my invention are preferably added to the emulsion as solutions in organic solvents, and. any suitable solvent such as alcohol, phenol, cresol, benzol, petroleum spirits may be employed for this purpose. In many cases I have found it desirable to dissolve or blend the aromatic nitroso compounds with sulfonated vegetable oils, such as sulfonated castor oil, and to employ the mixture in the form of an aqueous solution or emulsion. The amount of my demulsifying agent to be employed will vary with the nature of the emulsion to be treated; in general quantities of the order of -1000 parts per million are recommended and for most purposes it will be found that concentrations of 200-400 parts per million are satisfactory.

It should be understood that, in the commercial resolution of crude oil field emulsions, complete dehydration of the oil by a chemical demulsifying agent is not always obtained, nor is this always necessary. Accordingly, it should be understood that reference to the breaking and resolution of oil field emulsions in the foregoing specification and in the following claims is intended to include those cases in which only a partial resolution is obtained, since no single chemical demulsifying agent will bring about complete resolution of all petroleum emulsions.

What I claim is:

1. A process for breaking petroleum emulsions of the water-in-oil type which comprises subjecting the emulsion to the action of a demulsifying agent containing a nitroso aromatic compound selected from the group consisting of nitroso phenols and nitroso aromatic carboxylic acids.

2. A process for breaking petroleum emulsions of the water-in-oil type which consists in subjecting the emulsion to the action of a demulsifying agent containing a nitrosophenol.

3. A process for breaking petroleum emulsions of the water-in-oil type which consists in subjecting the emulsion to the action of a demulsifying agent containing a nitrosophenol and also containing a demulsifying agent of the surfaceactive type.

4. A process for breaking petroleum emulsions of the water-in-oil type which consists in subjecting the emulsion to the action of a demulsifying agent containing a nitrosophenol and also containing a sulfonated vegetable oil.

5. A process for breaking petroleum emulsions of the water-in-oil type which consists in subjecting the emulsion to the action of a demulsifying agent containing a nitrosophenol and also containing an ester of a sulfopolycarboxylic acid.

CHARLES F. BONNET. 

